Some physical objects incorporate or encompass cyclic or periodic motion, such as an electrical motor having a rotor that spins at a rotational speed or a human heart beating (i.e., performing contraction and relaxation) at a heart rate. The cyclic movement of the physical objects is observable or recordable by detection systems in the form of periodic or substantially periodic signals. The term “periodic or substantially periodic signals” (hereinafter also referred to as “periodic signals”) refers to the nature of the detected signals that usually have repetitive nominal waveform patterns although the exact waveforms and frequencies vary. Abnormal movement of a given physical object is thus detectable by analyzing the periodic signals.
For example, an Electrocardiograph (ECG) device is capable of converting the movement of a heart into one or more ECG signals from one or more combinations of leads attached to a person or animal undergoing examination. A trained medical care provider may identify certain abnormal movement(s) of the observed heart by comparing the ECG signals with a benchmark ECG signal of normal movement.